As part of a collaborative effort with the Department of Radiology at the Massachusetts General Hospital, we intend to assess the potential of liver-targeted, ferrite-based contrast agents to enhance the potential of magnetic resonance (MR) imaging for detection of liver metastases using a rat tumor model. Although published studies to date with MR contrast agents have involved only ions or ion-chelate complexes, unpublished data presented below suggest that such ferrite particles can act as powerful image enhancement contrast agents. One promising type of candidate particle has been identified. Advanced Magnetics' efforts will be directed toward the systematic synthesis of a variety of ferrite compounds which will be controlled for particle size, ferrite composition and chemical coating. These parameters are directed toward producing a non-toxic particulate (colloidal) contrast agent(s) of controlled size, size distribution, and chemical coating whose surface properties will allow for the efficient phagocytosis by the reticuloendothelial system of the liver but not by tumor nodules. The result of this selective uptake should allow major improvements in the contrast between normal and cancerous tissues. We expect that new MR contrast agents will provide additional tools for the study of organ physiology and metabolism and offer clinical advantages that can result in increased patient/sample throughput and reduced cost per examination.